1. Technical Field
The present invention relates to a technique that prints an image configured of an ink layer having a plurality of layers.
2. Related Art
As one of ink jet printers, a serial type ink jet printer is known which forms the image by ejecting ink from a printing head while moving the printing head in a main scanning direction and a sub-scanning direction. In addition, a technique is known which prints the image configured of an ink layer having a plurality of layers by using the ink jet printer.
For example, in JP-A-2006-247991, a technique is disclosed in which a base layer is formed using a white ink on a transparent printed medium and printing is performed using a process color ink on the formed base layer. In addition, JP-A-2006-247991 discloses a technique (hereinafter, also referred to as a nozzle dividing technique) which ejects one of the white ink and the process color ink using a nozzle group of the upstream side of the nozzle row which is formed in the printing head for each type of the ink and ejects the other ink using a nozzle group of the downstream side. According to the nozzle dividing technique, the ink layer having two layers can be formed while transporting the printed medium once over a length of the printed medium.
JP-A-2001-1560, International Publication No. 2005/105452 and JP-A-5-64870 are examples of the related art.
When the printed matter configured of the ink layer having five or more layers is printed using these techniques, various problems may occur. The printed matter configured of the ink layer having five or more layers can be a printed matter which forms, on a transparent printed medium, for example, a first color layer formed by a color ink, a first special gloss layer formed by a special gloss ink, a base layer formed by a white ink, a second special gloss layer formed by the special gloss ink and a second color layer formed by the color ink. The special gloss ink is ink expressing special gloss such as metallic effect. The printed matter can be a printed matter on which the image is visible from both surfaces of the printed medium.
However, when five layers are formed on one surface of the printed medium, the number of nozzles for each nozzle group which is divided is decreased if the configuration having five layers is made by dividing the nozzle rows in five and forming the divided each nozzle groups by one layer using the nozzle dividing technique described above. As a result, a printable range with one nozzle group is decreased and printing speed is extremely slow.
On the other hand, when the nozzle dividing technique is not used, since only one ink layer is formed during a process in which the printed medium is transported once over the length of the printed medium, it is necessary to repeat the process five to form the ink layer having five layers. As methods for repeating the transportation process of the printed medium, a method for automatically reversing the transportation direction of the printed medium and a method for repeatedly setting the printed medium by manual operation in an initial position may be considered. In any method, it is inevitable that the position of the printed medium is slightly shifted during a plurality of transportation processes. In other words, a relative position of each layer in a printed surface is shifted from a predetermined original position thereof. For example, when the position relationship between the first color layer and the first special gloss layer is shifted, special gloss effect which is expressed is varied. As a result, there is a concern that printing quality may be degraded.
In addition, when three layers are formed on one surface of the printed medium and two layers are formed on the other surface, a problem may occur in some cases, caused by printing on both surfaces of the printed medium. For example, when the printed matter of which both surfaces are printed is attached to a window of a shop so that a printed content is visible from any one of inside and outside of the shop, one of printed surfaces directly comes into contact with the window. In this case, there is a concern that the ink may be attached to the window. In other words, when peeling the attached printed matter, it is necessary to remove the attached ink.
As described above, a new printing technique is required which can preferably print a printed matter configured of an ink layer having five or more layers.